The present invention relates generally to diverter valves for use in pneumatic conveying systems and the like, and more particularly to a diverter valve having a novel seal arrangement which provides substantially improved seal life.
It is known to employ diverter valves in pneumatic conveying systems for transferring dry flowable particulate or pulverulent materials such as cement, ash, soot, powdered minerals, flour and coal dust and the like. Such systems generally employ a transfer or pressure vessel into which the particulate material is drawn, such as from the hold of a ship or railcar or the like, and from which the flowable material is discharged by way of a pneumatic convey line or conduit to a different location such as a remote storage silo or manufacturing facility. Depending upon the volume of material being transferred, or alternatively the volume capacity of the receiving facility or receptacle, a diverter valve may be utilized in the pneumatic convey line to facilitate diversion of material flow between one or more alternate receiving convey lines for transfer to alternate storage or operating facilities.
Diverter valves of the aforementioned type are known which employ a pair of plates supported in juxtaposed relation for relative movement therebetween, and wherein one of the plates has a port adapted for connection to a pneumatic convey input line and the other plate has a pair of ports adapted for connection to corresponding output convey lines such that selective relative movement between the plates effects alternate aligned positioning of the ports and associated convey lines to facilitate flow through either of the output convey lines. To establish a sealed condition between aligned ports, it is known to provide an annular seal about the port of each output convey line for sealing against the opposed plate. The annular seals are generally biased into sealing relation with the opposed plate surface by fluid pressure or mechanical spring means.
A significant drawback in the known diverter valves of the aforedescribed type is that the annular seals undergo substantial wear during relative movement between the juxtaposed plates when shifted to divert flow between one or more alternate convey lines. It will be appreciated that the greater the force biasing a seal into sealing relation with the opposed plate, the greater the wear experienced by the seal during actuation of the valve between alternate convey conditions, thus significantly reducing the life of the seal. Another problem incident to pressurized engagement of the annular seals against the opposed valve plate surface during relative movement between the valve plates is that a greater force is required to effect movement between the valve plates, thus requiring greater energy to effect operation of the diverter valve.